The focus of this proposal is to obtain an understanding of the motor control characteristics of the stereotypic movement disorders of the developmentally disabled, and in particular, those movements associated with tardive dyskinesia. Current characterizations of stereotypic behaviors rely largely on the natural observation of the observer and speculation about the appropriate categorization of movement disorders. It is proposed that a formal kinematic analysis of the movement disorders with subjects under neuroleptic medication and withdrawn from neuroleptic medication conditions and different task constraints will: (1) provide a description of the stereotypic movements that is consonant with movement parameters seen to reflect organizational coordination and control properties of the central nervous system; (2) allow comparison to matched 'normal' subjects on fundamental rhythmic and vocational activities and, while attempting to mimick the performance of stereotypic activities; (3) allow an examination of the effect of psychotropic drugs on the motor control characteristics of movement disorders; (4) provide a formal test of the observer checklist approach to characterizing stereotypic movements. The findings from the proposed experiments should provide a screening test than, for example DIS-Co, to assess tardive dyskinesia in various populations of mentally retarded people.